An increasing number of light fixtures utilize LEDs as light sources due to their lower energy consumption, smaller size, improved robustness, and longer operational lifetime relative to conventional filament-based light sources. Conventional LEDs emit light at a particular wavelength, ranging from, for example, red to blue or ultraviolet (UV) light. However, for purposes of general illumination, the monochromatic emitted light by LEDs must be converted to broad-spectrum white light.
Conventional white LEDs are typically constructed as phosphor-converted LEDs where a blue LED is covered with a phosphor coating that converts a portion of the emitted blue light to yellow light so as to create white light. The photometric characteristics of the emitted light, such as a color correlated temperature (CCT) value or chromaticity coordinates in the CIE 1931 color space, are generally fixed. While such conventional LED lighting devices may be suitable for some uses, commercial establishments may have different demands—e.g., preferring the CCT of the light to change throughout the day along with the circadian rhythm of individuals (e.g., employees, customers, etc.) exposed to the light. For example, the CCT of the white light may desirably be lower in the late evenings to facilitate a healthy sleep cycle and higher in the afternoon to combat afternoon fatigue. Consequently, there is a need for LED devices that can emit white light with an adjustable CCT value.